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5408 :: Difference between two dates

• Peter58 (orginal) [2019-10-27T10:46:10+01:00] view original

  Hi all... I'm looking for a simply way, to calculate the diff. between two dates ... in Days ! For example>

  import times

  let auj = format(now(), "d/MM/yyyy -- HH:mm") # Today's date... let deb = parse("04-09-2019", "dd-MM-yyyy") #an 'older' date... echo deb.format("dd-MM-yyyy")

  Actually, the result will be : 54

  Very thanks.

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• GULPF (orginal) [2019-10-27T11:38:28+01:00] view original

  Solution:

  import times
  let auj = now()
  let deb = parse("04-09-2019", "dd-MM-yyyy")
  echo (auj - deb).inDays
  Run

  Keep in mind that this assumes 24-hour days.

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• Peter58 (orginal) [2019-10-27T11:53:19+01:00] view original

  Good job... Quick and simply answer... Script work perfectly ! Thanks a lot :-)

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• cblake (orginal) [2019-10-27T14:39:52+01:00] view original

  If you need a larger range and only care about "dates" only, there is a pretty simple formula valid for all dates after 4800 BC in http://www.faqs.org/faqs/calendars/faq/part2/ question 2.16.1

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• jdf (orginal) [2022-01-27T03:33:02+01:00] view original

  std/times seems to have toEpochDay and fromEpochDay but they're not exported. It would be useful if they were!

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• cagyul (orginal) [2022-01-28T05:19:50+01:00] view original

  Or you can simply calculate the difference in their Julian day numbers.

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• jdf (orginal) [2022-01-28T13:15:12+01:00] view original

  Sure but is there an exposed implementation or would I be rolling my own?

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• cblake (orginal) [2022-01-28T19:44:26+01:00] view original

  Don't think there's an exposed impl, but here you go:

  proc julian*(year, month, day: int): int =
    let a = (14 - month) div 12 # See calendar FAQ$2.16.1
    let y = year + 4800 - a
    let m = month + 12 * a - 3
    (day + (153 * m + 2) div 5 + y * 365 +
      y div 4 - y div 100 + y div 400 - 32045)
  echo julian(2022, 1, 28) - julian(1970, 1, 1) # 19020
  Run

  When I ran date +%s just now I got 1643395370 divided by 86400 = 19020.7797453 which is just about right (in UTC) (18:42:50).

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